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Group transfers 4. Arylselenide aniondiaryl diselenide exchange
Author(s) -
Jacobson Barry M.,
Kook Alan M.,
Lewis Edward S.
Publication year - 1989
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610020506
Subject(s) - chemistry , nucleophile , acetonitrile , diselenide , group (periodic table) , diffusion , nmr spectra database , photochemistry , computational chemistry , spectral line , organic chemistry , thermodynamics , catalysis , physics , selenium , astronomy
Barriers for group transfers between nucleophiles have been postulated to be lowered when the transferring group can carry a considerable negative charge. Furthermore, anions readily subject to one electron oxidation appear to lead to lower barriers than do those of high oxidation potential. These suggestions are pursued here on the identity reaction ArSe − + ArSeSeAr → ArSeSeAr + ArSe − . Indeed the reaction is very fast, as shown by the appearance of only a single peak in the 77 Se‐NMR in an acetonitrile solution containing both ArSeNa and ArSeSeAr. The rate constant can be only very roughly estimated at low temperatures and dilute solutions, and is likely diffusion controlled for Ar = phenyl and p ‐methoxyphenyl. A stable intermediate (ArSe) 3 − , analogous to Br 3 − , is indicated, but quantitative stability could not be determined, from either the NMR or the UV spectra. Some properties of 77 Se‐NMR are discussed.